Whether it be safety systems, fuel economy, engines or quality, most automakers worldwide have raised their games, and differences between brands sold in the US are generally small. So it comes down to design - the way cars look inside and out - as the way manufacturers can set themselves apart in a wildly competitive market. "It's the only differentiator left," says Ford Motor Co. design chief J Mays. "If you don't love it, you've lost." At most companies, the design, once an afterthought, is now atop the food chain as cars and trucks are being developed. There's no better example than Chrysler's 300C sedan, a blockbuster hit with more than 500,000 sold since its 2004 debut. Its art deco look was different and far more elegant in 2004 than what was then bland competition. Designers are in a difficult position because they have to anticipate the future, keeping their cars fresh for several years without being too shockingly different. Yet if they are too conservative, their products look old as competitors come out with new vehicles. "The environment we're in is constantly changing," said Ed Welburn, General Motors Corp.'s vice president of design. "What's hot now, maybe its out of step six months from now. It is an incredible challenge." GM has elevated design so it is considered as vehicles are planned instead of at the end of the process. At Chrysler, the head of design in recent years has reported directly to the chief executive. Chrysler LLC design chief Trevor Creed said the pressure is on manufacturers to come up with the next 300C, a task easier said than done in a competitive marketplace. "I think it will become more and more difficult to create that big hit," he said in an interview at the North American International Auto Show in Detroit. Big hits like the 300C are a combination of design, powertrain and price, Creed said. "The 300C was the return of the rear-wheel-drive, all-American sedan. Bold looks at an incredibly affordable price," he said. "Pretty soon you've got Kia doing that and Hyundai doing that. So that's not exclusive any more." It is an art to come out with a car that is cutting-edge enough but does not offend buyers. At Hyundai Motor Co., designers try to anticipate what a car should look like three years beyond its debut, said chief designer Joel T. Piaskowski. "What the competition brings out next can age your existing design that much faster," he said. Designers also must balance looks with demands to be more aerodynamic for better fuel efficiency. Sometimes, according to Creed, the two conflict. Engineers from the company's wind tunnel come back with a shopping list, he said, and they usually compromise and meet aerodynamic needs while keeping the design character. "There's definitely trade-offs," Creed said. "We can't take it all out on design because the thing will look like a bar of soap." Interior design, which once came after the exteriors, now is center stage as most manufacturers invest more money in passengers' surroundings than in the past. GM, Welburn said, often cut costs from interiors at the 11th hour to stay within budget because it was too late to cut anywhere else. But that all changed about five years ago as the company recognized it needed first-class interiors to compete. "We made a big cultural shift," he said. "We really put a lot of our very best people - designers, sculptors, engineers - on interior design. When we're reviewing a project, we'll review the interior before we do the exterior, just to make sure it gets its fair amount of time in the design process." As Chrysler increases its investment, its interiors are becoming softer and more luxurious, Creed said. The next big hit, he said, may be in a smaller-volume segment, or it may simply be taking existing hit products like the Chrysler minivans and keeping them fresh so they remain must-haves for people. But inside or outside, there are risks as designers try to stay new and ahead of the competition. "It's a calculated risk," said Hyundai's Piaskowski. "As designers, as visionaries of the company, we feel like we have that under control."